1. Field of the Invention
The invention relates generally to valve covers and more specifically to safety valve covers.
2. Prior Art
Numerous valve covers exist, nominally to prevent the accidental or unauthorized operation of the valves they cover. However, many of them have shortcomings which prevent these goals from being achieved. Some covers have open or partially open tops which allow objects such as screwdrivers to be inserted into the cover and used to turn the valve wheel or other control element. Other covers use the valve wheel or other control element to prevent the removal of the cover. This creates problems because it allows the cover itself to be used to engage and turn the valve.
Use of the valve wheel to prevent removal of the cover can also create safety problems, in the event of a valve failure. If the valve fails, the valve wheel and the attached valve stem may be pushed out of the valve assembly, possibly at great speed depending upon the pressure of the line. If there is a valve failure and the valve wheel is all that is retaining the valve cover, the cover will be ejected with the valve wheel and stem, adding to the weight of the projectile.
Another problem in the prior art arises with the valves themselves. Plant environments can have hundreds and even thousands of valves within a relatively small space along pipe systems that can be mazelike in complexity. Many of these valves are similar in appearance and can be difficult to differentiate from one another simply by looking at the valves. In some plants, opening or closing the wrong valve may adversely effect environmental, health, or safety conditions at the plant and the surrounding area.
Another problem that the present invention is designed to address lies in the unrelated field of outboard motor propellers. Propellers start at $75 to $100 and rise to several hundred dollars in value, particularly for those made from stainless steel. In an outboard motor, they are typically attached by a single nut. The nut is exposed and can be removed in a matter of seconds with an air wrench. Once the nut is removed, the propeller may be simply slipped from the motor. The ease with which propellers may be removed makes them a favorite target for thieves. The problem is exacerbated by the frequency with which boats are stored in relatively unsecured areas, such as parking lots at motels or open boathouses on public lakes. The inventor is not aware of any commercially available lock designed to secure outboard motor propellers. In view of the foregoing shortcomings in the prior art, what is desired is a valve cover and propeller lock that meets the following objectives.
It is an object of the invention to prevent the unauthorized operation of valves.
It is another object of the invention to prevent the unintentional operation of valves.
It is another object of the invention to secure the valve stem in the event of a valve failure.
It is another object of the invention to identify valves.
It is another object of the invention to provide warnings about operation of valves.
It another object of the invention to prevent the theft of outboard motor propellers.
The invention comprises a plate having two sections and a cap. Each section of the plate has an indentation along its inner edge that forms an aperture when the sections are placed together in a closed position. The sections also preferably have an arm depending from each section with an inwardly facing lip at the distal end of the arm. When the sections are in the closed position, the arms come together to form a hollow column aligned with the aperture and the lips come together to form a constriction in the column. On the opposite side of each section are a set of sidewalls that form a circle when the sections are in the closed position. A cap fits over the sidewalls when the sections are in the closed position. The cap prevents the sections from opening while it is in place. It also prevents access to the objects contained within the cover. A tongue and groove assembly may be provided to retain the cap in place, and a plurality of lock apertures may be provided to allow the sections and the cap to be locked together. Alternatively, threads may be used for this purpose. By appropriately sizing the aperture in the plate or the constriction in the column, the cover will fit behind the locking nut of a valve assembly, around the hub of an outboard motor propeller, or around the shaft of a door knob. In the case of a valve assembly, the aperture or constriction should be sized to prevent the locking nut from passing through. With a propeller, the aperture or constriction should be sized to prevent the passage of the flared end of the hub. For a door knob, the aperture or constriction should prevent the passage of the knob itself.